How to Pass an Argument When Calling a View File

How to pass an argument when calling a view file?

You can pass a hash of parameters to the Haml method using the :locals key:

get '/' do
    haml :index, :locals => {:some_object => some_object}
end

This way the Ruby code in your Haml file can access some_object and render whatever content is in there, call methods etc.

How to access content of a file pass as an argument?

< is a redirection operator provided by your shell.

This operator opens the file on its right-hand side for reading, and, by default, remaps the standard input (stdin) of your program to be this file.

It is also possible to specify which file descriptor to remap with the form:

program [n]< file

wherein [n] is a number. The typical mapping between UNIX file descriptors and C Standard Library streams is

• 0 - stdin
• 1 - stdout
• 2 - stderr

but it is possible to open other file descriptors, and have your program read from them with man 2 read.

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Here's an example program. Note the differences between these two different sets of commands:

This

./a.out a b < file.txt

will print the strings a and b under the section listing the program arguments, and then it will print the contents of file.txt.

Whereas this

./a.out a b file.txt

will print the strings a, b, and file.txt under the section listing the program arguments, and then wait for you to type something in the terminal.

#include <stdio.h>

int main(int argc, char **argv) {
    size_t line = 0;
    char buffer[256];
    
    puts("--- argv ---");
                             
    for (int i = 0; i < argc; i++)
        printf("arg #%d : %s\n", i, argv[i]);
                             
    puts("--- stdin ---");

    while (fgets(buffer, sizeof buffer, stdin))
        printf("%4zu|%s", ++line, buffer);
}

How can I pass an argument while writing a file using python

You can get arguments by calling sys.argv[] array.

sys.argv[0] means script name itself.

You can then write it back to your file, open the file such as here.

Pass arguments when using the File protocol

I am assuming you are using Windows? If so, there is no way to pass a parameter using the "file://" syntax, as it is an Asynchronous Pluggable Protocol that does not accept parameters.

However, if you really need it, you can craft your own pluggable protocol that accepts parameters.

Here's an example:

An Asynchronous Pluggable Protocol Handler for data: URLs

Passing a file as a command line argument and reading its lines

...
// command line parameter
if(argv.length != 1) {
  System.err.println("Invalid command line, exactly one argument required");
  System.exit(1);
}

try {
  FileInputStream fstream = new FileInputStream(argv[0]);
} catch (FileNotFoundException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
}

// Get the object of DataInputStream
...

> java -cp ... Zip \path\to\test.file

How to pass text file as an argument in Ruby

On your shell, invoke the ruby script followed by the name of the .txt file, like this:

ruby foo.rb test_list.txt

The variable ARGV will contain references to all the arguments you've passed when invoking the ruby interpreter. In particular, ARGV[0] = "test_list.txt", so you can use this instead of hardcoding the name of the file:

File.open(ARGV[0]).each do |line|
    puts line
end

On the other hand, if you want to pass the content of the file to your program, you can go with:

cat test_list.txt | ruby foo.rb

and in the program:

STDIN.each_line do |line|
    puts line
end

Creating a function that takes in a text file as an argument

Can I recommend you try using Linq? e.g.:

 Boolean found = File
   .ReadLines(@"C:\MyFile.txt")               // <- Your file name
   .Any(line => line.Contains(word_to_find)); // <- Word to find

With Linq you don't need any methods to implement and have one line solution.

EDIT: in case that you have to find out words, e.g. "the", but not "then" you can modify the solution by using regular expressions instead of simple Contains():

  Boolean found = File
    .ReadLines(@"C:\MyFile.txt")               
    .Any(line => Regex.IsMatch(line, @"(^|\W)" + word_to_find + @"($|\W)")); 

passing files and values as parameter to a function in python

I would create a little class (give it a useful name) to encapsulate your data.
If your files grow you only have to change your create_lats

min_length = 1
max_length = 30

# delays
delay = 100

# Speed of light
c_vaccum = 3e8

#Little class to keep our data in one place 
class Lat:
    def __init__(self, filename, factor):
        self.filename = filename
        self.factor = factor
        self.file = open(filename, "w") #let the class open the file

#now our function needs only one parameter, neat!
def latcalc(lat):
    target_name = 0

    for length in range(min_length, max_length):
        if length < 2:
            target_name += (length / (lat.factor * c_vaccum)) #acces the class variable
        elif length == 2:
            target_name += delay
        else:
            target_name = target_name

        myline = "%s\t%s\n" % (length, target_name)
        lat.file.write(myline)

def create_lats():
    lats = []
    lats.append(Lat("file1.txt", 0.4))
    lats.append(Lat("file2.txt", 0.8))
    lats.append(Lat("file3.txt", 1))
    return lats

#loop over your lats created in create_lats
for lat in create_lats():
    latcalc(lat)
    lat.file.close() #close the file

How do I use a FILE as a parameter for a function in C?

You are lacking a function prototype for your function. Also, write is declared in unistd.h so that is why you get the first error. Try renaming that to my_write or something. You really only need the stdio.h library too as a side note, unless you plan on using other functions later. I added error checking for fopen as well as return 0; which should conclude every main function in C.

Here is what I would do:

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

void my_write(FILE *fp, char *str)
{
    fprintf(fp, "%s", str);
}

int main(void)
{
    char *str = "test text\n";
    FILE *fp;

    fp = fopen("test.txt", "a");
    if (fp == NULL)
    {
        printf("Couldn't open file\n");
        return 1;
    }
    my_write(fp, str);

    fclose(fp);

    return 0;
}

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